Infrared devices are used in many practical applications such as communications, security systems, and other modern electronic devices. In many of these applications, the sensitivity of the infrared detector is critical to its application. There have been many advances in the use of semiconductors and transistor structures for detecting infrared radiation or light. Many of these advances have resulted in faster, more responsive detectors, as well as detectors capable of detecting multi-color infrared radiation. One such detector is disclosed in U.S. Pat. No. 5,013,918 issuing to Choi on May 7, 1991, and entitled "Multi Color Infrared Photodetector", which is herein incorporated by reference.
In another publication entitled "10 Micrometer Infrared Hot Electron Transistors" by K. Choi, et al, Applied Physics Letters, Vol. 57 (Sep. 1990), Pages 1348-1350, an infrared detector is disclosed having an energy filter that selectively permits the high energy photocurrent to pass to the collector while rejecting the low energy dark current. The device sensitivity or detectivity is thereby enhanced.
While there are infrared photoconductor devices with adequate sensitivity for various applications, there is a continuing need to improve the detectivity or sensitivity of infrared detection devices.